1. Field of the Invention
The invention relates to lift assemblies for vehicle axle/suspension systems, and in particular to the means for operating such lift assemblies. More particularly, the invention is directed to a radio frequency system which controls the air springs that lift and lower the axle/suspension system of a heavy-duty vehicle such as a straight truck or a semi-trailer, wherein the use of radio frequency eliminates the need for a relatively expensive and inefficient hard-wired lift assembly control system.
2. Background of the Invention
Axle/suspension lift assemblies have been used for many years on heavy-duty vehicles such as tractor-trailers or semi-trailers, straight trucks such as dump trucks, and the like. Such heavy-duty vehicles typically include certain ones of their axle/suspension systems which are equipped to be lifted and lowered. For example, after dumping a load, the operator of a dump truck may choose to lift one of the axle/suspension systems to save it from wear and tear, since it is no longer required to support the additional load previously contained in the dump bed. Pneumatic lift air springs typically are utilized to accomplish the lifting operation. The lift air springs are inflated or deflated for raising or lowering, respectively, the axle/suspension system. Conversely, the ride air springs are deflated or inflated when the axle/suspension system is raised or lowered, respectively.
Since such heavy-duty vehicles have a variety of other functions that require control, such as operating the dumping function on a dump truck, it can be appreciated that the operator of the vehicle desires to remain in the cab to control these functions, rather than stepping out of the cab each time a function needs to occur, which can be inconvenient and/or dangerous. Thus, a conventional manner of controlling such functions as axle/suspension system raising and lowering has been to install an air control panel in the cab. A pneumatic supply line or conduit typically is run between a compressed air supply tank mounted outside of the cab, through the cab body, and is operatively connected to the control panel. Air feed lines in turn must also be operatively connected to the air controls, passed through the cab body and run to the rear of the vehicle for operative connection to the lift and ride air springs.
Although such an arrangement allows for relatively satisfactory pneumatic control of axle/suspension system lift assemblies from the cab by the operator of the vehicle, there are several disadvantages with such prior art control systems. First, long runs of conduit or air lines must be utilized, which is expensive and inefficient. More particularly, utilizing such long runs of air line results in delayed or slow response time of the air springs when a signal is sent from the air control panel in the cab to lift or lower the axle/suspension system. In addition, such a hard-wired system requires a relatively large control panel to be mounted in a very limited space within the vehicle cab. Also, materials in addition to the air lines are required such as mounting hardware and the like, and due to the large number of components, installation of such a pneumatically-controlled system on a straight dump truck can take up to about a day of labor by an installer, and can take even longer on semi-trailer dump-type trucks.
Therefore, a need has existed for a more efficient and inexpensive system for controlling axle/suspension system lift assemblies of heavy-duty vehicles. The present invention solves the above-noted problems by utilizing a radio frequency control system for the axle/suspension system lift assembly, which is capable of sending a radio frequency signal from a portable transmitter located in the vehicle cab to a radio frequency receiver mounted adjacent to the axle/suspension system to be lifted.
Objectives of the present invention include providing a control system for lift assemblies of vehicle axle/suspension systems, which is capable of controlling the lifting and lowering of the axle/suspension system without the use of large numbers of the components, including substantially long runs of air line.
Another objective of the present invention is to provide such a control system which enables faster response time of the controlled lift assembly when compared to response times achieved by prior art control systems.
An additional objective of the present invention is to provide such a control system which eliminates the need for mounting of a relatively large control panel within the vehicle cab.
A still further objective of the present invention is to provide such a control system which is economical, durable in use, easy to install, maintain, and replace.
These objectives and advantages are obtained by a control system for a function of a heavy-duty vehicle, the control system including, a radio frequency transmitter, a radio frequency receiver mounted adjacent to and operatively connected to an assembly which performs the function, so that an operator can actuate the transmitter to send a radio frequency signal to the receiver for controlling the function.